(-) Hydroxycitric acid HCA) occurs in the fruit rind of Garcinia species (G. Cambogia, G. indica and G. atroviridis). The first two species grow abundantly in India and the third occurs mostly in South East Asian countries. The success of this natural food product derived from Garcinia fruit has been documented and been in use since several centuries BC. Also known as "Kokum", the extracts of the fruit have been used as a tart flavoring in meat and seafood dishes, turned into a refreshing beverage that serves as a unique flavor enhancer, gourmet spice and a digestive after a heavy meal. In Ayurveda, the traditional ancient system of herbal medicine in India, Garcinia is also considered to be one of the prime herbs that are beneficial for the heart.
In more recent times, Garcinia has received worldwide attention as a nutriceutical for effective obesity control. Several scientists including at Hoffman-La Roche have established that HCA, the active ingredient in the fruit, prevents the conversion of excess carbohydrates to fat in animals. The energy released by the excess carbohydrate is converted into and stored as glycogen, a readily usable form of energy. Interestingly, it has been shown to inhibit ATP dependent citrate-lyase, a key enzyme in diverting carbohydrate to fatty acids and cholesterol synthesis (Sullivan et al. Lipids, 9:121 and 129 (1973), Sergio, W., Medical Hypotehsis 27:39 (1988)).
The age-old practice of consuming Garcinia rind as a food additive by inhabitants of Malabar and Konkan coast of the Indian penisula has established the safety of HCA. The isolation and chemical nature of (-) hydroxycitric acid from Garcinia rind are described in the publication of Lewis Y. S., et al. (Methods in Enzymology, 13:613 (1967) and in the patents (Indian patents 160753 & 178298 and U.S. Pat. Nos. 5536516 & 5656314).
It is believed that consumption of HCA influences the body metabolism leading to the saturation of glycogen receptors in the liver and a consequent transmission of signals of satiation to brain. Even as a food supplement, (-) HCA helps a person to lose/control weight in a natural way without affecting normal physical activities.
In view of its unique property, several health care formulations incorporating HCA are being sold across the counter in the Western markets. These include tablets, capsules, herbal teas, chocolate bars, milk shakes and other beverages. The active ingredient (HCA) from this insoluble HCA salt is released upon contact with hydrochloric acid in the stomach and absorbed through the intestine to exert its metabolic effect.
There is prior art on the preparation of a soluble tri-potassium salt of (-) HCA (Lewis Y. S., et al (Methods in Enzymology, 13:613 (1967), International Patent WO 96/36585, U.S. Pat. No. 08/440,968 filed). However, its alkaline nature and risks associated with the consumption of high potassium (.about.36%) makes this product unsuitable for HCA-based formulations.
In our earlier patents (Indian patent No. 178298 & U.S. Pat. Nos. 5536516, 5656314) which describes preparation of a concentrate of (-) hydroxycitric acid and its lactone in liquid form, comprising of several steps like water extraction of Garcinia rind containing (-) hydroxycitric acid and its concentration, acetone refinement of this concentrated water extract, evaporation of acetone, loading thus obtained refined extract on ion-exchange columns containing an anion exchange resin followed by a cation exchange resin, and finally evaporation of the free acid liberated from the ion-exchange process to said concentration. This liquid form of (-) hydroxycitric acid has problems of stability and half-life.
In addition, its highly acidic nature poses problems in formulating into beverage and various other food products without affecting their flavor and properties.
The object of this invention is to overcome the above drawbacks by developing a new soluble double metal salt of (-) hydroxycitric acid which will not pose any problem in formulating with beverages and various other food products without affecting their flavor and properties.
To achieve the said objective, this invention provides a new soluble double metal salt of group IA and II A of (-) hydroxycitric acid of general formula I and more particularly formula II as given below: ##STR1##
Where X is IA group metal: Li or Na or K or Rb or Cs or Fr
Where Y is IIA group metal: Be or Mg or Ca or Sr or Ba or Ra
where concentration of X in the salt varies from 1.5-51.0%,
the concentration of Y in the salts varies from 2.0-50.9%,
the concentration of HCA in the salts varies from 31.0-93.0% depending on the nature of X and Y. ##STR2##
concentration of sodium in the salt: 8.58%,
concentration of calcium in the salt: 14.92%
concentration of (-) hydroxycitric acid: 76.50%,
This invention further relates to a process for preparing the said soluble metal salt of group IA and IIA of (-) hydroxycitric acid of general formula I or more particularly formula II comprising:
Step 1: preparing (-) hydroxycitric acid liquid concentrate/solid lactone of hydroxycitric acid from Garcinia extract, PA1 Step 2: neutralizing the free (-) hydroxycitric acid present in the said (-) hydroxycitric acid liquid concentrate/solid lactone present (-) hydroxycitric acid with group IA metal hydroxides PA1 Step 4: precipitating the said solubilised group IIA metal salts of (-) hydroxycitric acid by adding aqueous polar solvent to get soluble IIA metal salt of (-) hydroxycitric acid PA1 i) treating the said Garcinia extract with group IA metal hydroxide to obtain soluble group IA metal salt of (-) hydroxycitric acid, PA1 ii) displacing completely the said group IA metal ions with group IIA metal ion by adding group IIA metal chlorides solution to precipitate insoluble group IIA metal salts of (-) hydroxycitric acid. PA1 iii) collecting the said precipitate of insoluble group IIA metal salt of (-) hydroxycitric acid and washing it with water, PA1 iv) adding a water soluble organic acid to the said precipitated insoluble group IIA metal salt of HCA to form a stronger salt of group IIA metal and release (-) hydroxycitric acid, PA1 v) repeating the steps (iii) and (iv) to form concentrate of (-) hydroxycitric acid, PA1 vi) decolorizing the said (-) hydroxycitric acid concentrate, if desired. PA1 i) extracting Garcinia rind with aqueous polar solvent and filtering, PA1 ii) heating the filtrate in vacuum at 50-80.degree. C. to evaporate the said polar solvent, PA1 iii) removing the water insoluble substances to get the (-) hydroxycitric acid concentrate, PA1 iv) decolorizing the said (-) hydroxycitric acid concentrate, if necessary. PA1 i) loading the Garcinia extract containing free (-) hydroxycitric acid on anion exchange resin column, PA1 ii) washing the said column with group IA metal hydroxide solution to get group IA metal salt of (-) hydroxycitric acid, PA1 iii) loading the said group IA metal salt solution of (-) hydroxycitric acid on cation exchange resin to get free (-) hydroxycitric acid, PA1 iv) heating the said free (-) hydroxycitric acid in vacuum to evaporate water and get the (-) hydroxycitric acid concentrate. PA1 v) decolorizing the said (-) hydroxycitric acid concentrate, if necessary. PA1 i) heating the (-) hydroxycitric acid concentrate at 67.degree. C. to form syrup of (-) hydroxycitric acid lactone, PA1 ii) drying and desiccating the said syrup to get solid mass of (-) hydroxycitric acid lactone. PA1 i) loading Garcinia extract containing free (-) hydroxycitric acid on an anion exchange resin column, PA1 ii) washing the said anion exchange resin column with Group IA metal hydroxide to obtain group IA metal salt of (-) hydroxycitric acid solution. PA1 iii) treating the said group IA metal salt of (-) hydroxycitric acid partially with group IIA metal chloride to get soluble double metal salt of group IA and IIA of (-) hydroxycitric acid.
Step 3: displacing partially group IA metal ions in the above salt solutions by adding group IIA metal chlorides to form soluble double metal salt of group IA and IIA of (-) hydroxycitric acid,
The free (-) hydroxycitric acid present in the step 2 is neutralized by three equivalents of group IA metal hydroxides.
Partial displacement of group IA metal ion in step 3 is carried out with one equivalent of group IIA metal chloride.
The soluble metal salt of hydroxycitric acid is obtained in powder from by spray drying prior to the solvent addition or spray drying water solubilised solvent precipitated material.
The said polar solvents are methanol, ethanol, propanol, isopropanol and acetone.
The (-) hydroxycitric acid concentrate in step 1 is prepared from the Garcinia extract by:
The water soluble organic acid used in step (iv) is an oxalic acid.
The (-) hydroxycitric acid concentrate in step 1 is also prepared from the Garcinia by:
The aqueous polar solvent used in step 1 is 80% acetone in water.
The (-) hydroxycitric acid concentrate in step 1 is also prepared from the Garcinia extract by:
The said (-) hydroxycitric acid concentrate is decolorized by heating with 2-5% activated charcoal, if desired.
The said lactone of (-) hydroxycitric acid in step 1 is prepared by:
A process for the preparation of soluble double metal salt of group IA and IIA of (-) hydroxycitric acid comprising:
Group IA metal hydroxides used are LiOH, NaOH, KOH, RbOH, CsOH and FrOH.
Group IIA metal chlorides BeCl.sub.2, MgCl.sub.2, CaCl.sub.2, SrCl.sub.2, BaCl.sub.2 and RaCl2.
The soluble double metal salt of group IA and IIA of (-) hydroxycitric acid is soluble sodium calcium salt of (-) hydroxycitric acid.
The process will now be described with reference to the following examples.